It's valid for anyone who bought an Xbox 360 within the last 12 months. Microsoft has also said anyone who paid for repairs on an out-of-warranty console, which would be covered by the new warranty, will receive a refund of the repair costs.
The company did not give any details as to why it didn't offer a one year warranty to begin with. However, it did say it was extending it "to be consistent with the standard one-year Xbox 360 warranty that is available throughout most of the world".
Microsoft made the change shortly before Christmas after some 3,300 petitioners complained the console was failing soon after the original 90-day warranty had finished. Microsoft has reportedly been charging between $50 (£30) and $129 (£70) for repairs.
There will not be any changes to the UK warranty as it already lasts 12 months.